Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: byEFxi18z4JZ4qw1omOPlP/mf+dgP4/Eb0kd4eAM9aZhtFiN0LnQKXrOI4u9QiXjZfLyltwHk5
 IHp7c0iwriJA==
IronPort-SDR: bVvdkknJA7bew7unweNqBq/BQ40Wtel/+Vm/lilbQhrFnelOxHyOfDvOHewpfnWcvaerzbrdZj
 IOZP6Q6YFEpg==
From:   Bard Liao <yung-chuan.liao@linux.intel.com>
To:     alsa-devel@alsa-project.org, vkoul@kernel.org
Cc:     vinod.koul@linaro.org, linux-kernel@vger.kernel.org, tiwai@suse.de,
        broonie@kernel.org, gregkh@linuxfoundation.org, jank@cadence.com,
        srinivas.kandagatla@linaro.org, rander.wang@linux.intel.com,
        ranjani.sridharan@linux.intel.com, hui.wang@canonical.com,
        pierre-louis.bossart@linux.intel.com, sanyog.r.kale@intel.com,
        mengdong.lin@intel.com, bard.liao@intel.com
Subject: [PATCH 05/11] soundwire: bus: update multi-link definition with hw sync details
Date:   Tue, 18 Aug 2020 10:41:14 +0800
Message-Id: <20200818024120.20721-6-yung-chuan.liao@linux.intel.com>
In-Reply-To: <20200818024120.20721-1-yung-chuan.liao@linux.intel.com>
References: <20200818024120.20721-1-yung-chuan.liao@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Hardware-based synchronization is typically required when the
bus->multi_link flag is set.

On Intel platforms, when the Cadence IP is configured in 'Multi Master
Mode', the hardware synchronization is required even when a stream
only uses a single segment. The existing code only deal with hardware
synchronization when a stream uses more than one segment so to remain
backwards compatible we add a configuration threshold. For Intel cases
this threshold will be set to one, other platforms may be able to use
the SSP-based sync in those cases.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 include/linux/soundwire/sdw.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 76052f12c9f7..9adbe4fd7980 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -827,6 +827,11 @@ struct sdw_master_ops {
  * @multi_link: Store bus property that indicates if multi links
  * are supported. This flag is populated by drivers after reading
  * appropriate firmware (ACPI/DT).
+ * @hw_sync_min_links: Number of links used by a stream above which
+ * hardware-based synchronization is required. This value is only
+ * meaningful if multi_link is set. If set to 1, hardware-based
+ * synchronization will be used even if a stream only uses a single
+ * SoundWire segment.
  */
 struct sdw_bus {
 	struct device *dev;
@@ -850,6 +855,7 @@ struct sdw_bus {
 	unsigned int clk_stop_timeout;
 	u32 bank_switch_timeout;
 	bool multi_link;
+	int hw_sync_min_links;
 };
 
 int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
-- 
2.17.1